The present invention relates to an improved side bearing for mounting on a railway car truck bolster that provides improved control to limit rock and roll characteristics of the railway car in service.
As shown in FIG. 1, a typical railway freight car truck 64 includes a pair of side frames 30, 32 supported on axle-wheel sets 34, 36. Bolster 38 extends between and is supported on springs 40 mounted on side frames 30, 32. Bolster center plate 28 includes a central opening 42. Side bearing pads 60 are provided laterally to each side of the center plate 28 on bolster 38. Side frames 30, 232 comprise a top member 44, compression member 46, tension member 48, column 50, pedestal 54, pedestal roof 56, wheel axle bearings 58, and bearing adapter 62. Side bearings are commonly used on railroad car trucks. Such side bearings are typically located on the truck bolster such as on side bearing pads 60, but may be located elsewhere on the bolster. Bolster 38 and side frames 30, 32 are usually unitary cast steel structures.
Typical side bearing arrangements are designed to control hunting of the railroad car. As a railroad car travels along the railroad track, a yaw excess motion can be induced in the railroad car truck. As the truck yaws, part of the side bearing is made to slide across the underside of a wear plate bolted to the railroad car body bolster. The resulting friction produces an opposing torque that acts to prevent such yaw motion. Another purpose of railroad car truck side bearings is control or limit the rock or roll motion of the car body. Most prior side bearing designs limited vertical travel of the side bearings.
Accordingly, it is an object of the present invention to provide an improved side bearing which will limit the vertical rock or roll motion of the railway freight car.
It is another object of the present invention to provide an improved side bearing which will provide improved control over the rock or roll motion of an empty railway freight car.